重庆工学院毕业设计 自动化立体仓库及堆垛机设计－立体仓库设计 文献翻译
Industrial Robots
A robot is an automatically controlled, reprogrammable, multipurpose, manipulating machine with several reprogrammable axes, [1]which may be either fixed in place or mobile for use in industrial automation applications.
The key words are reprogrammable and multipurpose because most single-purpose machines do not meet these two requirements. The term “reprogrammable” implies two things: The robot operates according to a written program, and this program can be rewritten to accommodate a variety of manufacturing tasks. The term “multipurpose” means that the robot can perform many different functions, depending on the program and tooling currently in use.
Over the past two decades, the robot has been introduced into industry to perform many monotonous and often unsafe operations. Because robots can perform certain basic tasks more quickly and accurately than humans, they are being increasingly used in various manufacturing industries. Structures of Robots
The typical structure of industrial robots consists of 4 major components: the manipulator, the end effector, the power supply and the control system, as shown in Fig.17.1.
Fig.17.1 Structures of Robots
The manipulator is a mechanical unit that provides motions similar to those of a human arm. It often has a shoulder joint, an elbow and a wrist. It can rotate or slide, stretch out and
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重庆工学院毕业设计 自动化立体仓库及堆垛机设计－立体仓库设计 文献翻译
withdraw in every possible direction with certain flexibility.
The basic mechanical configurations of the robot manipulator are categorized as cartesian, cylindrical, spherical and articulated. A robot with a cartesian geometry can move its gripper to any position within the cube or rectangle defined as its working volume. Cylindrical coordinate robots can move the gripper within a volume that is described by a cylinder. The cylindrical coordinate robot is positioned in the work area by two linear movements in the X and Y directions and one angular rotation about the Z axis. Spherical arm geometry robots position the wrist through two rotations and one linear actuation. Articulated industrial robots have an irregular work envelope. This type of robot has two main variants, vertically articulated and horizontally articulated.
The end effector attaches itself to the end of the robot wrist, also called end-of-arm tooling. It is the device intended for performing the designed operations as a human hand can. End effectors are generally custom-made to meet special handling requirements. Mechanical grippers are the most commonly used and are equipped with two or more fingers. The selection of an appropriate end effector for a specific application depends on such factors as the payload, environment, reliability, and cost.
The power supply is the actuator for moving the robot arm, controlling the joints and operating the end effector. The basic types of power sources include electrical, pneumatic, and hydraulic. Each source of energy and each type of motor has its own characteristics, advantages and limitations. An ac-powered or dc-powered motor may be used depending on the system design and applications. These motors convert electrical energy into mechanical energy to power the robot. Most new robots use electrical power supply. Pneumatic actuators have been used for high speed, nonservo robots and are often used for powering tooling such as grippers. Hydraulic actuators have been used for heavier lift systems, typically where accuracy was not also required.
The control system is the communications and information-processing system that gives commands for the movements of the robot. It is the brain of the robot; it sends signals to the power source to move the robot arm to a specific position and to actuate the end effector. It is also the nerves of the robot; it is reprogrammable to send out sequences of instructions for all movements and actions to be taken by the robot.
An open-loop controller is the simplest form of the control system, which controls the robot only by following the predetermined step-by-step instructions. This system does not have a self-correcting capability. A close-loop control system uses feedback sensors to produce signals that reflect the current states of the controlled objects. By comparing those feedback signals with the values set by the programmer, the close-loop controller can
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重庆工学院毕业设计 自动化立体仓库及堆垛机设计－立体仓库设计 文献翻译
conduct the robot to move to the precise position and assume the desired attitude, and the end effector can perform with very high accuracy as the close-loop control system can minimize the discrepancy between the controlled object and the predetermined references.
Robot Applications
The robot is a very special type of production tool; as a result, the applications in which robots are used are quite broad. These applications can be grouped into three categories: material processing, material handling and assembly.
In material processing, robots use tools to process the raw material. For example, the robot tools could include a drill and the robot would be able to perform drilling operations on raw material.
Material handling consists of the loading, unloading, and transferring of workpieces in manufacturing facilities. These operations can be performed reliably and repeatedly with robots, thereby improving quality and reducing scrap losses.
Assembly is another large application area for using robotics. An automatic assembly system can incorporate automatic testing, robot automation and mechanical handling for reducing labor costs, increasing output and eliminating manual handling concerns. Fig.17.2 is SCARA Robot for automatic assembly.
Fig.17.2 SCARA Robot for Automatic Assembly
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重庆工学院毕业设计 自动化立体仓库及堆垛机设计－立体仓库设计 文献翻译
工业机器人
机器人是一种自动控制的，可重复编程的，多功能的，由几个可重复编程的坐标系来操纵机器的装置，它可以被固定在某地，还可以是移动的以在工业自动化工厂中使用。
机器人的主要优点在于可重复编程和多功能性，因为大多数功能单一的机器不能满足这两种要求。“可重复编程”包含两层含义：机器人根据已设定的程序运转，并且这个程序可以被重写以适应多种制造任务。“多功能”意味着机器人可以拥有多种不同的功能，这依赖于当前正在使用的程序和工具。
经过过去 20 年的发展，机器人已经进入到工厂来完成许多单调的和不安全的操作任务。因为机器人可以比人更快而准确地完成某些基本任务，所以机器人正在大量地应用于各种制造企业。 机器人的结构
工业机器人的典型结构包含4 个主要部分：操纵器、终端执行机构、动力供给和控制系统，如图17.1 所示。
图 17.1 机器人的结构
操纵器是一个机械系统，进行类似于人的手臂的运动。它通常有一个肩关节、一个肘部和腕部。它能旋转或滑动，以一定的弹性在各个可能的方向上伸缩。机器人操纵器的基本机械构造可以分为：笛卡儿形，圆柱形，球形和铰接形。笛卡儿坐标式机器人可以在一个立方体或矩形范围内把手爪移到各个位置，这可界定为它的工作范围。圆柱坐标式机器人可以在定义的柱体范围内移动手爪。圆柱坐标式机器人可以通过在X 和Y 方向的线性运动和相对于Z 轴的一定角度的旋转来定位工作范围。球形手
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重庆工学院毕业设计 自动化立体仓库及堆垛机设计－立体仓库设计 文献翻译
臂几何形状的机器人通过两个旋转和一个线性运动定位腕部。铰接形工业机器人具有一种不规律的工作范围。这种类型的机器人具有两个重要变量：垂直铰接和水平铰接。
终端执行机构连接在机器人腕部的末端，也称为臂端工具。这是用来像人手一样完成所设计的操作的装置。终端执行机构一般都是定做的，以适合专用操作的需要。机械手是最常用的，一般装有两个或多个手指。选择一种特殊用途的合适的终端执行机构依赖于有效载荷、环境可靠性和价格等多个因素。
动力源是移动机械手，控制关节，操作终端执行机构的驱动器。基本的动力源包括电力，气动，液压3 种。每种能量和各种发动机都具有自身的特性、优点和局限性。选择交流或直流电动机依赖于系统的设计和用途。这些发动机把电能转化为机械能为机器人提供能量。大多数新型机器人采用电力驱动。气动驱动器应用于高速、非伺服机器人，也应用于动力驱动工具，如手爪。液压驱动器用于较重的提升系统，尤其是精确度要求不高的场合。
控制系统是通信和信息处理系统，由它发出指令以驱动机器人动作。它是机器人的大脑，它向动力源发出信号，把机器人手臂移到特定位置，并驱动终端执行机构。它也是机器人的神经系统，对机器人的所有运动及动作所发送的指令序列是可重复编程的。
一个开环控制器是控制系统的最简单的形式，它通过预定的按部就班的指令控制机器人。这样的系统没有自我纠错能力。闭环控制系统由反馈传感器产生信号，这些信号反映被控目标的当前状态。通过将反馈信号与程序员设定的值相对比，闭环控制器能引导机器人向准确的位置运动并实现期望的状态；终端执行机构可以高度精确的运作，因为闭环控制系统可以使被控目标与预定值间的误差达到最小。 机器人的应用
机器人是一种很特别的生产工具，因此，机器人应用的范围十分广泛。这些应用可以被划分为3 类：材料处理、材料搬运和装配。
在材料处理中，机器人用工具来加工和处理原材料。例如，机器人工具可包括钻头，从而可以在原始材料上执行钻孔操作。
材料搬运包括装载、卸载和转移制造设备上的加工零件。这些操作可以由机器人可靠地重复执行，因此提高了质量，减少了废料损失。
装配是机器人技术的另一个广泛应用。自动装配系统能合并自动测试、机器人自动控制和机械处理，以减少劳动成本，提高产量，消除人工操作的危险性。图17.2 所示是应用于自动装配的SCARA 机器人。
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立体仓库--文献翻译
